Mention Kotlin in README (#13725)

README.md

diff --git a/README.md b/README.md
index 892cd70..0536982 100644
--- a/README.md
+++ b/README.md
@@ -84,8 +84,8 @@
 Make your app come to life
 with platform APIs, 3rd party SDKs,
 and native code.
-Flutter lets you reuse your existing Java, Swift, and ObjC code,
-and access native features and SDKs on iOS and Android.
+Flutter lets you reuse your existing Java/Kotlin and ObjC/Swift code,
+and access native features and SDKs on Android and iOS.
 
 Accessing platform features is easy. Here is a snippet from our <a href="https://github.com/flutter/flutter/tree/master/examples/platform_channel">interop example</a>:
 
@@ -116,7 +116,7 @@
 is an easy and fast way to build beautiful mobile apps.
 If you are an experienced iOS or Android developer,
 you can use Flutter for your views and leverage much of your
-existing Java/ObjC/Swift investment.
+existing Java/Kotlin/ObjC/Swift investment.
 
 ### Build
 
@@ -132,7 +132,7 @@
   * Package manager
 * **Full-featured apps**
   * Interop with mobile OS APIs & SDKs
-  * Maven/Java
+  * Gradle/Java/Kotlin
   * Cocoapods/ObjC/Swift
 
 ### Optimize